So I'm opening this up again, because its a valid issue.
The issue is that on gnome wayland there is no "main" bash/zsh/... shell from which the xserver is started so the bash profiles aren't read and enviroment variables aren't set.
Upstream fixed this in this commit: https://gitlab.gnome.org/GNOME/gnome-session/commit/7e307f8ddb91db5d4051c4c792519a660ba67f35
This obviously doesn't work on Solus, because there is no /etc/profile but a /usr/share/etc/profile and so the login shell never gets run. I tried to manually fix that and see if it works afterwards, but unfortunally there seems to be another issue somewhere.
The obvious user facing issue this creates is that /snap/bin isn't added to the $PATH and /var/lib/snapd/desktop isn't added to $XDG_DATA_DIRS, so Snaps just don't show up in Gnome. The other issue is that $QT_QPA_PLATFORMTHEME is not set to gtk2, so Qt apps (eg. KeepassXC,...) isn't using *any* styling at all.
@taaem try this out for me.
Edit this file /usr/bin/gnome-session
Change /etc/shells to /usr/share/defaults/etc/shells on line 6 and see if it works
@sunnyflunk did that already but nothing changed, tried it with bash and zsh as my main login shell
The thing is that flatpak is added to path and working fine, because it is in /usr/share/gdm/env.d/... *but* its overwriting the XDG_DATA_DIRS variable there, if you comment that line out flatpak is broken but snaps are there.
Closing since Wayland support is not planned at this time and there has been multiple stack upgrades since then.